• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.892-898
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• 2007

This study aims to implement an efficient process management system for small and medium sized(local) construction companies and a performance management system for the Korean construction industry. The process management system by Lean Construction is Web 2.0 platform-based and creates clusters with numerous general contractors and sub-contractors, which will enable mutually organic process management. Plus, this system will enable them to compare project performance management by analyzing it during or after a project by collecting and accumulating lots of data occurring in pursuit of a project. These performance management cases will be of help in process planning during similar upcoming projects. This study is expected to somewhat reduce the burden of implementing a complicated process management protocol and system that Korean small and medium sized (local) construction companies experience with their web-based process management, and is supposed to realize accurate performance management with highly reliable data which are significantly accumulated within the database.

• Journal of Soil and Groundwater Environment
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• v.8 no.4
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• pp.27-35
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• 2003

The study site located in an industrial complex has a Precambrian age gneiss as a bedrock. The poorly-developed, disturbed soils in the study site have loamy-textured surface soil (1 to 2 m) and gravelly sand alluvium subsurface (2 to 6 m) on the top of weathered gneiss bedrock. The depth of the groundwater table was about 3.5 m below ground surface and increased toward down-gradient of the site. The hydraulic conductivity of transmitted zone (gravelly coarse sand) was in the range of 5.0${\times}$10$\^$-2/∼1.85${\times}$10$\^$-1/ cm/sec. The fine sand layer was in the range of 1.5${\times}$10$\^$-3/ to 7.6${\times}$10$\^$-3/ cm/sec. and the reclaimed upper soil layer was less than 10$\^$-4/ cm/sec. Toluene, ethylbenzene, and xylene (TEX) was the major contaminant in the soil and groundwater. The average depth of the soil contamination was about 1.5 m in the gravelly sand alluvium layer. At the depth interval 2.4∼4.8 m, the highest contamination in the soil is located approximately 50 to 70 m from the suspected source areas. The concentration of TEX in the groundwater was highest in the suspected source area and a lesser concentration in the center and southwest parts of the site. The TEX distribution in the groundwater is associated with their distribution in the soil. Microbial isolation showed that Pseudomonas flurescence, Burkholderia cepacia, and Acinetobactor lwoffi were the dominant aerobic bacteria in the contaminated soils. The analytical results of the groundwater indicated that the concentrations of dissolved oxygen (DO), nitrate, and sulfate in the contaminated area were significantly lower than their concentrations in the none-contaminated control area. The results also indicated that groundwater at the contaminated area is under anaerobic condition and sulfate reduction is the predominant terminal electron accepting process. The total attenuation rate was 0.0017 day$\^$-1/ and the estimated first-order degradation rate constant (λ) was 0.0008 day$\^$-1/.

• Journal of the Korea Concrete Institute
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• v.13 no.4
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• pp.329-335
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• 2001

Recently, in many laboratories and institutes it is being studied on the high flowing concrete widely, which has high fluidity, non-segregation ability and fillingability, and sometimes being applied to the construction field actually. And the fluidity properties of high flowing concrete are influenced according to the several factors ; binder content, water/binder ratio and water content etc. This is an experimental study to compare and analyze the effect of water/binder ratio and water content on the properties of high flowing concrete. For this purpose, the mix proportion of high flowing concrete according to water/binder ratio(W/B : 0.30, 0.35, 0.40, 0.45) and water content (W : 155, 165, 175, 185 kg/㎥) was selected. And then slump-flow, V-lot, L-passing test in fresh concrete, and compressive strength, freezing and thawing test in hardened concrete were peformed. According to test results, it was found that the viscosity of all those high flowing concrete with the water content 175 kg/㎥ was satisfied with 50 cm pass time of slump flow prescribed by Japanese Architectural Standard Specification (JASS 5) - from 3 to 8 seconds. And non-segregation ability of concrete with W/B 0.35 was better than the other mix proportions. Especially, the compressive strength after curing 24 hours(1 day) of all high flowing concrete was higher than that prescribed by JASS 5(50 kgf/㎠).

• Journal of the Korean GEO-environmental Society
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• v.12 no.1
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• pp.71-80
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• 2011

In period of rapid economic development, as doing river conservation work by using harmful materials environmental pollution has adversely effected humans, animals and plants frequently. For recovery of environmental pollution it needs a lot of time and cost. Therefore, in this study, in order to take an environment-friendly method which is also economical and durable both results of the laboratory model test and field test were compared and analyzed. According to the results of the laboratory model test, those methods such as concrete paving, asphalt paving, bentonite mat, stabilized soil method and mixed soil method have small amount of seepage, but on the other hand compaction soil, grassland and permeable materials have considerable amount of seepage. The results of field test show a similar tendency with laboratory test and have been satisfied to assess standard of domestic water permeability below $1.0{\times}10^{-7}cm/sec$ and unconfined compressive strength is also than 1.0MPa so it has been satisfied about standard. In conclusion, as compaction rate increased, as unconfined compression strength increased and coefficient of permeability decreased.

• Journal of Korea Water Resources Association
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• v.54 no.spc1
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• pp.1195-1204
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• 2021

Recently, local torrential rain have become more frequent and severe due to abnormal climate conditions, causing a surge in human and properties damage including infrastructures along the river. In this study, water surface elevation prediction algorithm was developed using the LSTM (Long Short-term Memory) technique specialized for time series data among Machine Learning to estimate and prevent flooding of the facilities. The study area is Jamsu Bridge, the study period is 6 years (2015~2020) of June, July and August and the water surface elevation of the Jamsu Bridge after 3 hours was predicted. Input data set is composed of the water surface elevation of Jamsu Bridge (EL.m), the amount of discharge from Paldang Dam (m³/s), the tide level of Ganghwa Bridge (cm) and the number of tweets in Seoul. Complementary data were constructed by using not only structured data mainly used in precedent research but also unstructured data constructed through wordcloud, and the role of unstructured data was presented through comparison and analysis of whether or not unstructured data was used. When predicting the water surface elevation of the Jamsu Bridge, the accuracy of prediction was improved and realized that complementary data could be conservative alerts to reduce casualties. In this study, it was concluded that the use of complementary data was relatively effective in providing the user's safety and convenience of riverside infrastructure. In the future, more accurate water surface elevation prediction would be expected through the addition of types of unstructured data or detailed pre-processing of input data.

• Journal of the Korean earth science society
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• v.26 no.5
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• pp.395-403
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• 2005

This study is focused on the relationship between snowfall and the Bowen’s Ratio (sensible heat flux/latent heat flux) through calculation of heat exchange between air and sea for snowfall events in Jeju Island from 1993 to 2003. The four weather stations for this study are located at Jeju, Seoguipo, Seongsanpo and Gosan in Jeju Island. In order to improve the reliability of snowfall forecast, the Bowen’s Ratio for snowfall, which includes influences from the atmosphere such as wind, is compared with the temperature difference between air and sea for snowfall. As a results, in the case for fresh snowfall, the minimum temperature differences between air and sea were 10, 12.3, 11.5, and $14.3^{\circ}C$ at Jeju, Seoguipo, Seongsanpo and Gosan, respectively. The probabilities of fresh snowfall were 26, 29, 13, and $23\%$, respectively, when the temperature differences were higher than the previous values. On the other hand, the minimum Bowen ratios were 0.59, 0.60, 0.65 and 0.65 at Jeju, Seoguipo, Seongsanpo and Gosan, respectively. The probabilities of fresh snowfall were 33, 70, 31 and $58\%$ respectively, when the Bowen ratio is higher than those. The reason for this is because the probability of fresh snowfall with the Bowen ratio was higher than the probability with temperature difference between air and sea. This result occurred because heat exchange by wind increased the probability of snowfall, along with the temperature difference between air and sea, and the Bowen ratio. Therefore, snowfall forecast of Jeju Island is significantly influenced by the sea, whereas forecast with Bowen ratio seems to have higher reliability than that with the temperature difference between air and sea. The data analysis for the ten-year period $(1993\~2002)$ showed that when each fresh snowfall was within 0.0 to 0.9cm, the average Bowen’s ratio was 0.63 to 0.67, and when each fresh snowfall was 1.0 to 4.9 cm, the average Bowen’s ratio was over 0.72. Therefore, fresh snowfall shows a proportional relationship with the Bowen’s ratio during snowfall.

• Radiation Oncology Journal
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• v.16 no.1
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• pp.71-79
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• 1998

Purpose : The objective of this study is to introduce our installation of a non-commercial 3D Planning system, Plunc and confirm it's clinical applicability in various treatment situations. Materials and Methods : We obtained source codes of Plunc, offered by University of North Carolina and installed them on a Pentium Pro 200MHz (128MB RAM, Millenium VGA) with Linux operating system. To examine accuracy of dose distributions calculated by Plunc, we input beam data of 6MV Photon of our linear accelerator(Siemens MXE 6740) including tissue-maximum ratio, scatter-maximum ratio, attenuation coefficients and shapes of wedge filters. After then, we compared values of dose distributions(Percent depth dose; PDD, dose profiles with and without wedge filters, oblique incident beam, and dose distributions under air-gap) calculated by Plunc with measured values. Results : Plunc operated in almost real time except spending about 10 seconds in full volume dose distribution and dose-volume histogram(DVH) on the PC described above. As compared with measurements for irradiations of 90-cm 550 and 10-cm depth isocenter, the PDD curves calculated by Plunc did not exceed $1\%$ of inaccuracies except buildup region. For dose profiles with and without wedge filter, the calculated ones are accurate within $2\%$ except low-dose region outside irradiations where Plunc showed $5\%$ of dose reduction. For the oblique incident beam, it showed a good agreement except low dose region below $30\%$ of isocenter dose. In the case of dose distribution under air-gap, there was $5\%$ errors of the central-axis dose. Conclusion : By comparing photon dose calculations using the Plunc with measurements, we confirmed that Plunc showed acceptable accuracies about $2-5\%$ in typical treatment situations which was comparable to commercial planning systems using correction-based a1gorithms. Plunc does not have a function for electron beam planning up to the present. However, it is possible to implement electron dose calculation modules or more accurate photon dose calculation into the Plunc system. Plunc is shown to be useful to clear many limitations of 2D planning systems in clinics where a commercial 3D planning system is not available.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.56-63
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• 2018

The management of Combined Sewer Overflows(CSOs) and Separated Sewer Overflows(SSOs) discharge directly to the effluent system in an untreated state, which occurs when the facility capacity is exceeded due to heavy rain, has become an important issue in recent years as the heavy rain becomes a regular phenomenon. Despite the continuous development of filtration technology, targeting densely populated urban areas, CSOs are rarely applied. Therefore, this study was carried out to optimize the process to apply CSOs in a pilot-scale horizontal flow filtration system with a rope-type synthetic fiber. The research was carried out in two steps: a preliminary study using artificial samples and a field study using sewage. In the preliminary study using an artificial sample, head loss of the filter media itself was analyzed to be approximately 1.1cm, and the head loss was increased by approximately 0.1cm as the linear velocity was increased by 10m/hr. In addition, the SS removal efficiency was stable at 81.4%, the filtration duration was maintained for more than 6 hours, and the average recovery rate of 98% was obtained by air backwashing only. In the on-site evaluation using sewage, the filtration duration was approximately 2 hours and the average removal efficiency of 83.9% was obtained when belt screen (over 450 mesh) was applied as a pre-treatment process to prevent the premature clogging of filter media. To apply the filtration process to CSOs and SSOs, it was concluded that the combination with the pre-treatment process was important to reinforce the hydraulic dimension for the stable maintain of operation period, rather than efficiency. Compared to the dry season, the quality of incoming sewage was lower in the rainy season, which was attributed to the characteristics of the drainage area with higher sanitary sewerage. In addition, the difference in removal efficiency according to the influent quality of the wet season and dry season was small.

• Journal of Korean Society of Archives and Records Management
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• v.5 no.1
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• pp.79-105
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• 2005

This study is that the name from Tagjijunjeol is compared with the actual papers used in historical documents. I have selected the families having had influencing power in Gyungi-Do(京畿道), Gyungsang-Do(慶尙道), Jeonra-Do(全羅道), Chungcheung-Do(忠淸道), and analyzed 1504 articles of historical documents owned by those families. I checked up each papers used in historical documents in it's shape of screens, density, raw material. I cannot find the feature of it's region, but prominent feature according to the types and period of historical documents. At first, I have surveyed the impressions of screen marks in papers. The number of strips can be divided into two cases, around 10 and around 17. The case around 17 is similar to the number seen in the book paper of the early Joseon Dynasty, but the case around 10 is rare. Dard Hunter said in his book, published in 1933, that screens were made of Korean grass(Miscanthus sp.) at that time in Korea. I guess the impressions of screen marks of the case around 10 was made of Korean grass, Miscanthus sp.. The case around 10 and the case around 17 were not different in period, but the contemporary appearance. However, if we look into the change of strips' number, we can learn that it becomes more dense as time goes by. The intervals of hair stitch, contrary to book paper, have appeared irregularly and a short hair stitch was frequently found between long hair stitches. This was the result of fastening extra stitch to increase the firmness of strips, as the part of screens which was frequently touched by hands would wear out easily. Then, have look into the density. Each kinds of historical documents had a wide range of density. But the average have had relationship with the kinds of paper written in Tagjijunjeol. The historical documents having the same item of paper have kept similar densities. From the density variation of Gosingyoji(告身敎旨), the letter of appointment the official rank over 5 by king, based on time periods, we can see a great disparity between before and after Imjin-waeran war. Before Imjin-waeran war paper's quality was high, right after Imjin-waeran war went abruptly down, and went gradually up just from 1650's, but since 1700's quality has not risen more, kept the value. On the contrary, the density of Gyocheop(敎牒), the letter of appointment the official rank under 5 by the Ministry of Personnel and the Ministry of Military, have not had a great disparity according to time periods, but had a lower density than Gosingyoji. Joseon Dynasty has strictly divided Gosingyoji appointing the official rank over 5 from Gyocheop appointing the official rank under 5, it seems to distinguish the appointment by king from the appointment by Ijo(吏曹), the Ministry of Personnel and Byeongjo(兵曹), the Ministry of Military.

• Korean Journal of Heritage: History & Science
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• v.57 no.2
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• pp.6-25
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• 2024

This study concentrated on a report on the results of smelting experiments conducted eight times by the Jungwon National Research Institute of Cultural Heritage, put together the goals and results of the operation, and examined changes in the content of experiments and in the experimental results. First, changes related to operation, such as the ratio of raw materials to fuel and the presence or absence of additives, were reviewed depending on the operation goal. In addition, the results of metallurgical analysis of raw materials, formations, and byproducts were summarized and reviewed by comparing them with materials excavated from the ruins. The operation method varied up to the eighth smelting experiment in terms of iron ore roasting, additives, and raw material/fuel ratio. After reviewing the results again, pure iron with a low carbon content began to be confirmed through metallurgical analysis. As a result, it was confirmed that the charging ratio of raw materials and fuel plays an important role depending on the purpose of production. In addition, most of the products are gray cast iron, and it was deemed that this is due to changes in the internal structure of the pig iron while it was left in the furnace for a long time. The iron was an ingot that was in a molten state even though the carbon content did not reach 4.3%, where the process reaction takes place, and it was deemed to have been caused by excessive operating temperature. Based on the previously reviewed results and the structure and shape of the experimental furnace used in other ironmaking technology restoration experiments, this study finally attempted to restore the structure of an ancient iron smelting furnace, including the furnace's upper structure. By comprehensively referring to the remaining conditions of the excavated iron smelting furnace and the characteristics of the blow pipe, the form of the ancient iron smelting furnace was subdivided into six categories: furnace wall thickness, furnace height, blower height, blow pipe size, furnace inner wall shape, and top shape, and a restoration plan was proposed. To improve the problems of the restoration plan and the Jungwon National Research Institute of Cultural Heritage's experiments that have been conducted through continuous trial and error, an experiment that reflects changes in operating methods by lowering the furnace height and controlling the blowing volume is necessary.